JP7594736B2 - How to collect copper wire - Google Patents

Description

The present invention relates to a method for recovering copper wire from shredded waste electronic and electrical equipment.

Waste electronic circuit boards and waste electrical equipment (hereafter referred to as waste electronic and electrical equipment) contain various copper wires. When the crushed scraps of such waste electronic and electrical equipment are reused as copper smelting raw materials in order to make effective use of resources, the copper wire fragments become entangled due to vibrations during the transport and sorting processes, and clumps of fragments that contain other fragments are gradually formed. Such clumps of fragments can cause various equipment problems, such as clogging of sieves during sorting, overloading of motors during the transport process, and reduced sorting accuracy, so it may be necessary to remove the copper wires from the crushed scraps of waste electronic and electrical equipment in advance.

Patent Document 1 discloses that, as a pre-treatment for separating raw materials containing valuable metals that can be processed in a smelting process from the crushed scraps of waste electronic and electrical equipment, lump copper wire scraps contained in the crushed scraps are removed by picking, and the picking method described includes a worker manually picking out the lump copper wire scraps or a robot mechanically removing the lump copper wire scraps. However, this picking method is intended to remove lump copper wire scraps contained in the initial crushed scraps, and cannot remove lump copper wire scraps formed by vibrations in the sorting process and transport process of the crushed scraps, and therefore the above-mentioned equipment failure is not fully resolved.

Non-Patent Document 1 describes a method of crushing small household appliances, recovering the crushed scraps that fall under a sieve with an 8 mm mesh size, loading the scraps into a rotating drum, and rotating the drum at 80% of the critical rotation speed for 10 minutes or more to form interlocking copper wire scraps in which copper wires bent by the rotational motion interlock with each other. This method is an effective means of mitigating the above-mentioned equipment failures, since it is possible to collect and separate the copper wire scraps scattered in the crushed scraps as interlocking copper wire scraps. However, since the rotation speed of the drum is high, even though interlocking copper wire scraps are formed, the proportion of the interlocking copper wire scraps that are destroyed by the impact of the high-speed rotation is high, and the recovery rate of the interlocking copper wire scraps is low. Therefore, although a large amount of energy is consumed for high-speed rotation, the elimination of equipment failures in the rear stage of the rotating drum is limited. In addition, there is a problem that the interlocking copper wire scraps are fragile and easily disintegrate due to the vibration of the sieve and are mixed in under the sieve.

JP 2020-37068 A

Minerals Engineering,(Netherlands), 2018, Vol. 129, p. 54-62

The present invention provides a copper wire recovery method that solves the above-mentioned problems in conventional methods for recovering copper wire from crushed scraps of waste electronic and electrical equipment. Specifically, in a method in which the crushed scraps are loaded into a rotating drum to form an assembly of entangled copper wires, the critical rotation speed of the rotating drum is controlled within a certain range to sufficiently form a copper wire entanglement that is difficult to disintegrate, thereby providing a copper wire recovery method that increases the recovery rate of copper wire.

… [Ａ]
〔２〕上記回転処理工程の処理時間が５分以上である上記[１]に記載する銅線の回収方法。
〔３〕上記回転処理工程の後に、形成された銅線絡合体を他の破砕屑から分別する工程を有する上記[１]または上記[２]の何れかに記載する銅線の回収方法。
〔４〕上記分別工程において、上記破砕屑の粒径より大きく～上記銅線絡合体の粒径より小さい目開きの篩によって該銅線絡合体を他の破砕屑から分別して回収する上記[３]に記載する銅線の回収方法。
The present invention relates to a method for recovering copper wire, comprising the following steps:
[1] A method for recovering copper wires, comprising a rotational processing step of storing crushed scraps of waste electronic and electrical equipment in a rotating drum and rotating the drum to form an aggregate in which copper wires contained in the crushed scraps are entangled with each other, the rotating drum being of a type in which the drum body is installed horizontally (the cylindrical axis is horizontally oriented) and rotated, and the contents of the drum are lifted upward along the inner circumference of the drum by the rotation of the drum body, and then the above-mentioned aggregate is formed by the impact of the contents falling from the drum,
A method for recovering copper wire, characterized in that the rotation speed of the rotating drum is controlled to 30% to 60% of the critical rotation speed represented by the following formula [A], thereby forming ball-shaped copper wire entangled bodies in which the copper wires are entangled with each other.
(In the following formula [A], Cs is the critical rotation speed (rpm), g is the gravitational acceleration (m/s2 ⁾ , and R is the radius of the rotating drum (m))

… [A]
[2] The method for recovering copper wire described in [1] above, wherein the treatment time of the rotation treatment step is 5 minutes or more.
[3] A method for recovering copper wire according to either [1] or [2] above, comprising a step of separating the formed copper wire entanglement from other crushed scraps after the rotating treatment step.
[4] The method for recovering copper wire according to the above [3], wherein in the separation step, the copper wire entanglement is separated and recovered from other crushed debris using a sieve having openings larger than the particle size of the crushed debris and smaller than the particle size of the copper wire entanglement.

… [Ａ]
[Specific explanation]
The present invention relates to a method for recovering copper wires, which includes a rotational processing step of storing crushed scraps of waste electronic and electrical equipment in a rotating drum and rotating the drum to form an aggregate in which copper wires contained in the crushed scraps are entangled with each other. The rotating drum is of a type in which the drum body is installed horizontally (the cylindrical axis is horizontally oriented) and rotated, and the contents of the drum are lifted upward along the inner circumference of the drum by the rotation of the drum body, and then the above-mentioned aggregate is formed by the impact of the contents falling from the drum.
This is a copper wire recovery method, characterized in that the rotation speed of the rotating drum is controlled to 30% to 60% of the critical rotation speed represented by the following formula [A], thereby forming ball-shaped copper wire entangled bodies in which the copper wires are entangled with each other.
(In the following formula [A], Cs is the critical rotation speed (rpm), g is the gravitational acceleration (m/s2 ⁾ , and R is the radius of the rotating drum (m))

… [A]

The method of the present invention is a method for recovering copper wire from the crushed waste of waste electronic and electrical equipment. The waste electronic and electrical equipment includes crushed waste electronic circuit boards and various types of crushed electrical equipment. The size of the crushed waste is not limited, but generally, it is preferable that the size is approximately 10 mm or less. The crushed waste contains copper wire fragments as well as resin fragments and miscellaneous fragments of aluminum and iron. The copper wire fragments also include coated copper wire fragments and uncoated copper wire fragments.

The rotating drum used may be of any size that can accommodate the usual amount of crushed debris. A typical usual amount is about 20% to 40% by volume of the drum. The rotating drum may be of a type in which the cylindrical drum body is installed horizontally (with the cylindrical axis horizontal) and rotated about the cylindrical axis. In this type of rotating drum, as the drum body rotates, the contents of the drum are lifted upward along the inner circumference of the drum, and as the rotation continues, the upper part of the contents leaves the inner circumference of the drum and performs a parabolic motion toward the inside of the drum, before falling to the inner circumference of the drum or onto the surface of the bed, where it is subjected to an impact, causing the elongated crushed debris to bend and become entangled with each other.

The copper wires contained in the crushed debris stored in the rotating drum are bent by the impact of this rotational fall, forming an aggregate in which multiple long, thin copper wires are entangled with each other. At this time, coated copper wires and highly rigid crushed debris are difficult to bend, and plastics are crushed, so neither of these are likely to form an entangled aggregate, and mainly uncoated copper wires form an entangled aggregate.

When the drum rotates too fast, the number of drops increases and the impact of the drops becomes greater, so although an aggregate of entangled copper wires is formed, the aggregate that is formed falls apart due to the impact of the drop, or becomes brittle and easily crumbles when subjected to the impact.

The method of the present invention controls the rotation speed of the rotating drum to form a ball-shaped aggregate of copper wires entangled with each other that is resistant to collapse. In the present invention, such a ball-shaped aggregate of copper wires entangled with each other that is resistant to collapse is called a copper wire entanglement. Specifically, the method of the present invention forms a sufficient amount of the above copper wire entanglement by controlling the rotation speed of the rotating drum to 30% to 60% of the critical rotation speed. Note that in Non-Patent Document 1, the drum rotation speed is 80% of the critical rotation speed, and there is no recognition of forming a copper wire aggregate that is resistant to collapse by limiting the rotation speed.

… [Ａ]
上記式[Ａ]において、Ｃｓは回転臨界速度(rpm)、ｇは重力加速度(m/s^２)、Ｒは回転ドラの半径(m)である。

The critical rotation speed of the rotating drum is expressed by the following formula [A] .

… [A]
In the above formula [A] , Cs is the critical rotation speed (rpm), g is the gravitational acceleration (m/s ² ), and R is the radius of the rotating drum (m).

If the rotation speed is less than 30% of the critical rotation speed, the impact of the fall is reduced and it is difficult to sufficiently form the copper wire entanglement, and if it exceeds 60%, the rotation speed is too fast and the impact of the fall increases, destroying the copper wire aggregate that is formed or making it brittle and prone to crumbling, which is undesirable.

The rotational processing time using the rotating drum is preferably 5 minutes or more. If the rotational processing time is about 2 minutes, a copper wire recovery rate similar to that of Non-Patent Document 1 can be achieved, but if the rotational processing time is 5 minutes or more, the copper wire entanglement is sufficiently formed, and the copper wire recovery rate can be significantly improved.

The copper wire recovery method of the present invention can include a step of separating the formed copper wire entangled body from other crushed debris after the above-mentioned rotation processing step. This separation step can utilize, for example, sieving, which separates and recovers the copper wire entangled body from other crushed debris using a sieve with mesh sizes larger than the particle size of the crushed debris of waste electronic and electrical equipment and smaller than the particle size of the copper wire entangled body. In addition to this type of sieving, a wide variety of methods can be used to separate the copper wire entangled body by utilizing differences in particle size and shape between the copper wire entangled body and other crushed debris.

According to the method of the present invention, copper wires contained in the shredded scraps of waste electronic and electrical equipment can be easily and efficiently separated from other shredded scraps. Therefore, by using this method in the recycling process of the shredded scraps, particularly in the sorting process of the shredded scraps in non-ferrous metal smelters and pre-treatment of the transport process for smelting, equipment failures that were seen in conventional processing methods can be avoided.

1 is a graph showing the relationship between the rotation speed of the drum and the weight of the copper wire entanglement. 1 is a graph showing the relationship between the inner diameter of the drum and the weight of the copper wire entanglement.

Examples of the present invention will be described below.
[Example]
20 kg of waste electronic circuit boards were crushed by a biaxial crusher, and then classified with a sieve with a mesh size of 10 mm, and the crushed pieces including copper wires that fell under the sieve were collected. 1350 g of the crushed pieces were charged into a rotating drum made of SUS with an inner diameter of 210 mm and a length of 200 mm, and both ends were covered (filling rate 30 volume %), and the drum was rotated for 15 minutes at a rotation speed of 40% of the critical rotation speed (hereinafter referred to as 40% Cs). At this time, the rotation of the rotating drum was stopped every 2.5 minutes, and the ball-shaped copper wire entangled bodies formed inside were taken out and their weights were measured, and after the measurements, the drum was returned to the inside of the drum and the rotation treatment was continued. After the 15 minutes of treatment in the rotating drum, the copper wire entangled bodies inside the drum were taken out and their particle size and weight were measured. Then, the copper wire entangled bodies were classified with a sieve with a mesh size of 2 cm, and the copper wire entangled bodies were collected on the sieve, and other crushed pieces were collected below the sieve. The crushed scraps that fell under the sieve were subjected to gravity separation using a table separator, and the presence or absence of new lump copper wire scraps that were generated was confirmed (Test A1).
Test A2 was carried out in the same manner as Test A1, except that the drum rotation speed was set to 30% of the critical rotation speed Cs.
Test A3 was carried out in the same manner as Test A1, except that the drum rotation speed was set to 60% of the critical rotation speed Cs.

Test A4 was conducted in the same manner as Test A1, except that a rotating drum having an inner diameter of 105 mm was used and the amount of crushed chips charged into the drum was 350 g (filling rate: 30% by volume).
Test A5 was carried out in the same manner as Test A1, except that a rotating drum having an inner diameter of 315 mm was used and the amount of crushed chips charged into the drum was 3,050 g (filling rate: 30% by volume).

Comparative Example
Test B1 was conducted in the same manner as Test A1, except that the drum rotation speed was set to 20% of the critical rotation speed Cs.
Test B2 was carried out in the same manner as Test A1, except that the drum rotation speed was set to 70% of the critical rotation speed Cs.
Test B3 was carried out in the same manner as Test A1, except that the drum rotation speed was set to 80% of the critical rotation speed Cs.
In the same manner as in Test A1, except that the drum was not rotated and the copper wire was not removed, the crushed scraps were subjected to gravity separation in a table separator, and the presence or absence of new lump copper wire scraps generated during the process was confirmed (Test B4).

The results of the tests A1 to A3 and B1 to B4 are shown in Table 1. The relationship between the treatment time of the rotating drum and the amount of the entangled copper wires formed is shown in Figure 1. For the tests A4 and A5, the relationship between the inner diameter of the rotating drum and the amount of the entangled copper wires formed is shown in Figure 2.
As shown in Test B1, when the drum rotation speed was 20% Cs, the rotation speed was insufficient, and the weight of the entangled copper wires formed was about 10 g. As shown in Tests A1 to A3, when the drum rotation speed was 30 to 60% Cs, a entangled copper wire of about 20 g was formed in a treatment time of 5 minutes. In addition, the particle size of the entangled copper wires after a treatment time of 15 minutes had grown large.
On the other hand, as shown in Tests B2 to B3, when the drum rotation speed was 70 to 80% Cs, the amount of entangled copper wires was reduced compared to Tests A1 to A3 (rotation speed 30 to 60% Cs). Thus, when the drum rotation speed was 30 to 60% Cs, the entangled copper wires were efficiently recovered.

As shown in Figure 2, even if the drum inner diameter is changed to 105 mmφ (Test A4) or 315 mmφ (Test A5), the weight ratio of the copper wire entanglement formed at a drum rotation speed of 40% Cs remains almost unchanged. Therefore, it was confirmed that, even if the drum inner diameter is changed, similar results to those of Tests A1 to A3 can be obtained by controlling the drum rotation speed to 30% to 60% of the critical rotation speed.

As shown in Test B4, if the copper wire in the crushed debris was not removed by drum rotation processing, the copper wire contained in the crushed debris became entangled on the feed box or deck during table dressing, generating a large number of clumped copper wire scraps, which interfered with the dressing operation. Also, as shown in Tests B1, B2, and B3, when the drum rotation speed was less than 30% Cs or more than 60% Cs, the amount of copper wire entanglements formed was less than in Tests A1 to A5, and the copper wire contained in the crushed debris was not sufficiently recovered. As a result, the amount of clumped copper wire scraps generated during table dressing increased, causing equipment trouble. On the other hand, as shown in Tests A1 to A3, when processing was performed with a drum rotation speed of 30 to 60% Cs, almost no clumped copper wire scraps were generated during table dressing, and no equipment trouble occurred.

Claims (4)

A copper wire recovery method including a rotation processing step of storing crushed scraps of waste electronic and electrical equipment in a rotating drum and rotating the drum to form an aggregate in which copper wires contained in the crushed scraps are entangled with each other, the rotating drum is of a type that is installed with a drum body oriented horizontally (with a cylindrical axis oriented horizontally) and rotated, and the contents of the drum are lifted upward along the inner circumference of the drum by the rotation of the drum body, and then the aggregate is formed by the impact of the contents falling from the drum,
A method for recovering copper wire, characterized in that the rotation speed of the rotating drum is controlled to 30% to 60% of the critical rotation speed represented by the following formula [A], thereby forming ball-shaped copper wire entanglements in which the copper wires are entangled with each other.
(In the following formula [A], Cs is the critical rotation speed (rpm), g is the gravitational acceleration (m/s2 ⁾ , and R is the radius of the rotating drum (m))

… [A] The copper wire recovery method according to claim 1, wherein the processing time of the rotation processing step is 5 minutes or more. A method for recovering copper wire as described in claim 1 or claim 2, which includes a step of separating the formed copper wire entanglement from other crushed debris after the above-mentioned rotating process. 4. The method for recovering copper wire according to claim 3, wherein in the separating step, the entangled copper wires are separated and recovered from other crushed debris using a sieve having openings larger than the particle size of the crushed debris and smaller than the particle size of the entangled copper wires.

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